1. Field of the Invention
The present invention relates to illuminated information displaying apparatus and more particularly to illuminated signs having changeable panels bearing numbers and letters with the source of illumination automatically activated and deactivated by a photoelectric cell preset to turn on the illumination source upon reaching normal dusk conditions and preset to turn such source off upon reaching normal sunrise conditions.
2. General Background
Different patents directed to illuminated signs for displaying changeable numbers and letters are known in the art.
In some illuminated signs such as neon signs, the light source is carried in and made a part of the letters, numbers or other characters forming the message. The letters, numbers and other characters are generally exposed and not readily changeable.
The second type of illuminated sign is comprised of a translucent front face having letters or numbers or other characters painted thereon with opaque paint and has a light source behind the face so that the entire face of the sign, with the exception of the opaque portion, is illuminated, thus providing a visible message during the day and night. The message on this type of sign is not easily changeable.
The third type of illuminated sign is comprised of a translucent face having a light source therebehind and generally having some type of track means on the exterior of the face such that the numbers, letters and other indicia characters can be retained in a desired sequence in front of the translucent face so as to spell out the message and be visible at night. The letters, numerals and other indicia are changeable in this type of sign. A prior art search of this type of illuminated sign that provides means for a changeable display message reveals that different patents directed to such structure have been issued.
U.S Pat. No. 4,373,284 entitled "Illuminated House Number Sign" issued to D. L. Crane and discloses an illuminated sign having a frame enclosed by a transparent cover. Grooved tracks are utilized to receive and retain display plates which have light transmitting portions therein in the shape of letters or numbers. A central light source provides illumination and the translucent sheet diffuses the light so that a uniformly bright message appears when the light source is energized and selected plates are abutted end to end in the tracks.
U.S. Pat. No. 3,414,999 entitled "Illuminated Sign" issued to L. Mason and discloses an illuminated sign having removable indicia illuminated from within.
U.S. Pat. No. 2,893,148 entitled "Illuminating Fluorescent House Number Fixture" issued to M. Figman and discloses a fluorescent house number fixture having removable indicia members mounted along the length of a fluorescent tube.
U.S. Pat. No. 1,831,181 entitled "House Numbering Device" issued to C. M. Koster and discloses an illuminated sign having removable and interchangeable numbers.
U.S. Pat. No. 1,081,646 issued to R. K. Witz and discloses an illuminated display sign having removable transparent plates bearing letters or other characters.
U.S. Pat. No. 1,208,870 entitled "Combined Light and Illuminated Sign" issued to E. H. Whitlock and discloses an illuminated sign.
U.S. Pat. No. 1,448,881 entitled, "Combination Number Reflector And Hall Light" issued to J. P. Theis and discloses an illuminated sign for displaying numbers or letters having a housing with a set of grooves therein for inserting panels bearing numbers or letters therein for illumination by an electric light.
The Applicant has provided an improved illuminated display apparatus in which the panels displaying the information interlock with each other, and, in which the illumination source is automatically activated and deactivated by a photoelectric cell preset to turn the source of light on upon reaching normal dusk conditions and turn such source off upon reaching normal sunrise conditions.